Purpose:Oculocardiac reflex (OCR)
is a frequent event during strabismus surgery. The aim of this study is to compare
the preventive effect of intravenous lidocaine and hyoscine on OCR.

Methods:This prospective,
randomized clinical trial was performed on 75 patients (5-63 years old) underwent
strabismus surgery. Patients divided randomly into three groups. Intravenous
hyoscine (0.2 mg/kg), lidocaine (1.5 mg/kg) and distilled water were injected
before induction with propofol for each group respectively under standard
monitoring. Heart rate, blood pressure and/or cardiac dysrrythmia were recorded
immediately before/after injection and muscle hooking. Decrease of heart rate more
than 20%, hypotension (decrease more than 20% in systolic or diastolic
pressure) or any cardiac dysrrythmia were defined as OCR.

Results: One hundred and
thirty-six muscles were hooked during strabismus surgery. OCR was observed in
44 hooked muscles (32.3%). Reflex was observed in hyoscine (34.2%), lidocaine
(24.9%) and control (40.9%) groups (p=0.12). The most stretched muscles which
caused OCR were medial rectus (56.8%) and lateral rectus (36.3%) muscles. OCR
was greater in patients with age between 5-10 years (56%).

Conclusion: Intravenous lidocaine
and N-buthylbromide hyoscine both could reduce OCR occurrence but the
difference was not statistically significant compared to the control group. OCR
was seen greater in young patients (5-10 years old). Some patients (specially
children) need intervention to restore normal condition.